Ameritech Corp.'s $1-million sponsorship of the largest-ever exhibit of French Impressionist Claude Monet's artwork turned out to be right on the money.

Since the exhibit opened July 22 at the Art Institute of Chicago, it has put the Chicago-based telecommunications company's name alongside an art phenomenon that's drawing record crowds from around the world, jamming museum phone lines and local hotels.

Ameritech's own prepaid phone card decorated with a Monet design is being test-marketed in the Art Institute's gift shop, which is selling as much as $100,000 in Monet-related merchandise per day, say museum officials.

Last month, the Metropolitan Museum of Art in New York opened an exhibit with an even more explicit marketing twist: 350 works by 18th-and-19th-century Spanish painter Francisco de Goya, sponsored by Hispanic foods marketer Goya Foods of Secaucus, N.J.

Simultaneously, the Philadelphia Museum of Art opened an exhibit of work by 1920s-era photographer Tina Modotti, sponsored exclusively by pop culture superstar Madonna, one of the photographer's biggest fans.

"This is our first celebrity-sponsored exhibit, but it's typical of the new sources of funding we're looking to develop as the $1-million sponsorships become fewer and farther between," said Mari Jones, special assistant to the museum's director for exhibition sponsorship.

The same museum will open a major exhibit of French painter Paul Cezanne's work next spring sponsored by Advanta, a Horsham, Pa.-based financial services company. The exhibit will coincide with Advanta's new national brand campaign.

At the Los Angeles County Museum of Art, "less money is coming from big conglomerates like IBM," and funding is increasing from smaller companies recognizing the marketing power of arts sponsorships for the first time, said Sonya Kay Levy, head of corporate giving for the largest art museum in the Western U.S.

The first L.A. County Museum of Art sponsorship by May Co.'s Southern California-based Robinsons-May department store takes place in November with "The American Discovery of Ancient Egypt." The exhibit, appearing from Nov. 5 to Jan. 21, coincides with the store's holiday sales season.

Chicago's Sara Lee Corp. is sponsoring a Degas exhibit at the Art Institute in 1996. A longtime arts sponsor, the company has increased its direct cash grants 4% this year to $4.1 million, supporting a wide variety of cultural projects.

"Our commitment to arts sponsorship is very long and deep," said Robin S. Tryloff, executive director of the Sara Lee Foundation.

"Other companies may be just getting into it more heavily, but for us, it's always been an important focus."